Systemd Cheat Sheet

Commands and unit-file syntax for managing services, timers, and system state with systemd on modern Linux distributions.

2 PagesIntermediateFeb 2, 2026

systemctl Basics

Control and inspect services.

bash

systemctl start nginx           # Start a service nowsystemctl stop nginx            # Stop a servicesystemctl restart nginx         # Restart a servicesystemctl reload nginx          # Reload config without restartsystemctl enable nginx          # Start automatically at bootsystemctl disable nginx         # Remove from bootsystemctl status nginx          # Show current state and recent logssystemctl is-active nginx       # Print active/inactivesystemctl daemon-reload         # Reload unit files after editing

Service Unit File

Define a custom long-running service.

ini

# /etc/systemd/system/myapp.service[Unit]Description=My ApplicationAfter=network.target[Service]Type=simpleUser=appuserWorkingDirectory=/opt/myappExecStart=/opt/myapp/bin/start.shRestart=on-failureRestartSec=5Environment=NODE_ENV=production[Install]WantedBy=multi-user.target

Timer Unit (cron alternative)

Schedule a service to run periodically.

ini

# /etc/systemd/system/backup.timer[Timer]OnCalendar=dailyPersistent=true[Install]WantedBy=timers.target# /etc/systemd/system/backup.service[Service]Type=oneshotExecStart=/usr/local/bin/backup.sh# Enable with: systemctl enable --now backup.timer

Logs & Debugging

journalctl and troubleshooting commands.

journalctl -u nginx- Show logs for a specific unit
journalctl -u nginx -f- Follow logs in real time (like tail -f)
journalctl -b- Show logs since the current boot
journalctl -p err- Filter logs by priority (err, warning, info, etc.)
systemctl list-units --failed- List all units currently in a failed state
systemd-analyze blame- Show which units took longest to initialize at boot

Pro Tip

After editing any unit file, always run 'systemctl daemon-reload' before starting/restarting the service — otherwise systemd keeps using the cached in-memory version of the unit.

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